川中地区侏罗系大安寨段页岩岩相类型及储层特征

通过岩心薄片鉴定、扫描电镜观察、X射线衍射分析与TOC含量检测等技术，精细划分了川中地区侏罗系大安寨段页岩岩相类型，并对各岩相的储集空间类型、物性和含气性等特征进行了分析，确认了优势岩相，并结合岩相与沉积相的纵向发育特征，指出了优势开发层段。研究结果表明：①川中地区大安寨段页岩储集空间以与黏土矿物相关孔隙和颗粒边缘孔为主，孔隙度为0.31%~8.55%，平均为3.97%；渗透率为0.001~12.185 mD，平均为0.659 mD；气的质量体积一般高于1.0 m³/t，其分布特征与孔隙度具有高度一致性。②研究区大安寨段页岩岩相可划分为6个大类13个小类，其中中高有机碳含量的介壳灰质黏土质页岩岩相有机质丰度、脆性矿物含量、孔隙度和含气量均最高，为最具优势的岩相，中高有机碳含量的粉砂质黏土质页岩岩相其次，中高有机碳含量的黏土质页岩岩相虽然其有机质丰度较高，但裂缝欠发育，具有一定的地质勘探潜力。③研究区大安寨段优势岩相主要分布在大二亚段的半深湖亚相，这也是有利的勘探方向。

Lithofacies types and reservoir characteristics of shales of Jurassic Da'anzhai member in central Sichuan Basin

Based on the observation of cores,thin sections,scanning electron microscope and the results of X-ray diffraction analysis and TOC content detection,the shale lithofacies of Jurassic Da'anzhai member in central Sichuan Basin was divided,and reservoir space types,physical properties and gas-bearing properties of each lithofacies were analyzed to confirm the dominant lithofacies. Combined with the vertical development characteristics of shale lithofacies and sedimentary facies,the dominant development zones were defined. The results show that:(1)The shale reservoir space of Da' anzhai member is mainly composed of clay mineral related pores and particle edge pores. The porosity ranges from 0.31% to 8.55%,with an average of 3.97%,and the permeability is 0.001-12.185 mD,with an average of 0.659 mD. The total gas content of shale is generally greater than 1.0 m³/t, and its distribution is highly consistent with porosity.(2)The shale lithofacies of Da'anzhai member in the study area can be divided into 6 categories and 13 sub-categories. Among them,shell limy clay shale lithofacies with medium-high organic carbon content has the highest organic matter abundance,brittle mineral content,porosity and gas content,which is the most dominant lithofacies,followed by silty clay shale lithofacies,clay shale lithofacies has high organic matter abundance but underdeveloped fractures,which has geological exploration potential.(3)The dominant lithofacies of Da'anzhai member in the study area is mainly distributed in the semi-deep lacustrine subfacies of Da 2 sub-member which is a favorable exploration zone.